Those who know me know that I use some pretty strong cautions when discussing the use of silicone on boats. There are places where it is certainly necessary, Beckson products for example, but beyond those few instances it can be one of the most contaminating substances on a boat.
I rebedded this chain plate recently and found it to the a perfect example of just why silicone, can be such a bad choice of product for some applications.
The owner of this boat potted all his chain plates sealing the surrounding core from moisture, a real +1 !! He then proceeded to bed them with silicone a -100......Doh'...... They then leaked pretty quickly. He then judiciously cleaned the surfaces of what he assumed was all the silicone, using multiple chemicals such as Acetone, MEK and Toluene, and re-bedded but......
This is how the cover plate came off after being bedded with a "polyurethane marine sealant"... One small area of adhesion and the rest was stuck like an egg in a non-stick frying pan.
And how the cover plate came off... The brownish color is mold & mildew from water sitting in there. The new sealant stuck to NOTHING due to the contamination from the previous bedding job.. Trust me, if you THINK you got all the silicone, think again....
Just this one chain plate took nearly an hour with grinders, ScotchBrite, sand paper, a Dremel and lots of Acetone to get it clean enough to re-bed.
Please think of these photo BEFORE you bed stuff on your boat...
I rebedded this chain plate recently and found it to the a perfect example of just why silicone, can be such a bad choice of product for some applications.
The owner of this boat potted all his chain plates sealing the surrounding core from moisture, a real +1 !! He then proceeded to bed them with silicone a -100......Doh'...... They then leaked pretty quickly. He then judiciously cleaned the surfaces of what he assumed was all the silicone, using multiple chemicals such as Acetone, MEK and Toluene, and re-bedded but......
This is how the cover plate came off after being bedded with a "polyurethane marine sealant"... One small area of adhesion and the rest was stuck like an egg in a non-stick frying pan.

And how the cover plate came off... The brownish color is mold & mildew from water sitting in there. The new sealant stuck to NOTHING due to the contamination from the previous bedding job.. Trust me, if you THINK you got all the silicone, think again....

Just this one chain plate took nearly an hour with grinders, ScotchBrite, sand paper, a Dremel and lots of Acetone to get it clean enough to re-bed.
Please think of these photo BEFORE you bed stuff on your boat...